As many of you might already know, the FBI does not get involved in local cases, including murder, unless the crime itself is connected to something that extends beyond the local boundaries of local law enforcement. Special agent Dale Cooper was dispatched to Twin Peaks because similarities to Theresa's murder matched Laura's and also the fact that Theresa's murder happened in Oregon and Laura's in Washington also gives it FBI jurisdiction since the suspect in the case is obviously crossing state lines. However, the audience is never told why Cole dispatched Special Agent Chet Desmond out there, to which he presents Lil that delivers the special message that states the murder is a Blue Rose case. It's funny that the film Twin Peaks - Fire Walk With Me was supposed to answer all the loose end questions when in fact, in typical TP fashion, it simply just presented more.